The features of 3500 patients with head injury who attended accident and emergency departments in Scotland during 1974 are described. These represented 10 per cent of all attenders at these departments. Recent alcohol consumption was noted in 25 per cent of adult males; this was commonest amongst those who were victims of assault or pedestrians involved in traffic accidents. Forty-one per cent of patients had scalp wounds; 58 per cent had radiographs of the skull taken and of these 2.7 per cent had fractures of the skull. Although 20 per cent of patients had altered consciousness at some time, only 5 per cent showed any evidence of impaired consciousness when seen at hospital. Twenty-three per cent of those attending were admitted to hospital. Criteria which are important when assessing whether a head-injured patient should be admitted to hospital are listed.